1. Field of the Invention
This invention relates to room temperature vulcanizable elastomers compositions and methods for preparing such compositions.
2. Description of the Prior Art
Room temperature vulcanizable silicone elastomer compositions curable through a number of mechanisms are known in the art. Some room temperature vulcanizable silicone elastomers cure by exposure to moisture through hydrolyzable functionality. The silicone elastomer compositions of this invention contain acetoxy functionality to allow cure at room temperature. Such compositions are described in U.S. Pat. Nos. 3,035,016; 3,077,465; and 3,274,145.
While prior art compositions have been commercially successful, their adhesion to certain types of substrates is a continuing problem.
One approach to provide the necessary adhesion of elastomeric materials to all types of substrates has been the development of priming systems. Such priming systems are undesirable in that they require additional steps and additional time in the process of bonding surfaces together.
Plueddemann in U.S. Pat. No. 3,455,877 describes organosilicon epoxides useful in the preparation of coating resins, laminates, and as intermediates in the preparation of other organosilicon materials. The Plueddemann patent describes the epoxytrialkoxysilanes used in this invention.
Nitzsche et al. in U.S. Pat. No. 3,131,161 have disclosed the use of epoxide compositions in high viscosity siloxane polymer formulations to produce improved tear properties. The silicone rubber stocks are cured with an organic peroxide and heat or with an alkylorthosilicate, alkylpolysilicate, or alkylhydrogensiloxane and a monocarboxylic metallic acid salt in the presence of moisture.
U.S. Pat. No. 3,076,726 by Ault et al. uses an epoxytriacetoxysilane of a type described in the above U.S. Pat. No. 3,455,877 with a methylpolysiloxane to obtain improved rubbery coatings which are particularly useful for purposes of release.
In spite of the advances made in obtaining bonding of elastomeric materials to substrates, problems still remain. The adhesion of the previous acetoxy containing room temperature vulcanizable silicone elastomers to glass and aluminum surfaces, particularly on long exposure to moisture, has not been satisfactory.